[unreadable] It is a challenge to obtain low abundant and/or secretory proteins/peptides (secretomes) from animals in vivo. Our laboratory has developed a novel technique to address this challenge which utilizes capillary ultrafiltration (CUF) probes to capture secretomes in vivo. Capillary ultrafiltration involves a vacuum applied to semipermeable membrane fibers to extract fluid containing secretory molecules from the interstitial space. The CUF probes also provide a simple means to obtain a small-volume sample from living biological systems. We have successfully identified and sequenced the secretomes directly by mass spectrometry, bypassing the traditional proteomics approaches which are primarily based on the 2D electrophoresis gels. In this proposal, we will use the well-established UV-induced fibrosarcoma tumor progressor/regressor model system to exploit the technique of CUF probes to collect in vivo secretomes. Tumor secretomes will be identified using mass spectrometry (MALDI-TOF MS and Q-TOF 2 MS/MS) and enzyme-linked immunosorbent assay (ELISA). In parallel, we will optimize this technique by performing high-throughput mass spectrometry (MALDI-TOF-TOF) and Cytokine Antibody Arrays. We believe that using CUF probes/Mass spectrometry will be a powerful tool which can be applied to other animal models and other human diseases. [unreadable] [unreadable] [unreadable]